BGS technic KG
Bandwirkerstr. 3
D-42929 Wermelskirchen
Tel.: 02196 720480
Fax.: 02196 7204820
www.bgstechnic.com
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BGS 1924
Thread Cutting Set, M3 - M12, 21 pcs.
CONTENT
Taps for thread sizes:
M3x0.5 - M4x0.7 - M5x0.8 - M6x1.0 - M8x1.25 - M10x1.5 - M12x1.75
Each thread size a taper tap, a second tap and a finishing tap.
INSTRUCTIONS
Please read and follow these instructions to reach a proper threading and longer tool-life. Taps and
dies are tools of high precision. They are produced from high-quality alloy steel, heat treated and
tempered for a hardness of 58-61 HRC. Check the hardness of your workpiece before starting thread-
cutting by a regular machinist's file. In case the workpiece can be easily filed, you may proceed with
your thread-cutting.
TAPS
•
To cut an internal thread, select a proper drill-size as per the table shown below, the tap of the
desired size and tap-wrench.
•
The proper hole-size is very important in the formation of good threads. An oversized hole results
in reduced thread-high an undersized hole will overload the tap and will probably cause damage
of the tool or even the workpiece.
•
Select a tap with the required size. Included in the set are for each thread size a taper tap (1
ring), a second tap (2 rings) and a finishing tap (without a ring), which are to be used in that order
for fabricating a thread.
•
Secure the tap by the square in the tap-wrench
•
Fix the workpiece in a bench-vise or by using clamps and start threading by turning the wrench in
clockwise direction. Great care must be taken to start the tap square to the hole. As the tap is
turned it bites into the metal and leads into the hole.
•
After the tap has been started, the metal-chips that flow into the flute spaces must be broken to
relieve pressure on the tap. This is accomplished by reversing the tap-direction every 1/4 to 1/2
revolution depending on the tightness encountered. Providing lubrication to the cutting edges
while tapping will result in smoother threads and longer tap-life.
•
Continue threading until the tap passes through the workpiece or it reaches the bottom of the
hole.
•
When tapping a blind hole (one that does not pass entirely through the workpiece) take care in
drilling to provide clearance at the bottom for metal-chips and the starter-threads. These
chamfered threads on the end of the tap will not cut full threads.
Table for drill hole (tap)
Nominal
Pitch
Drill Ø
Nominal
Pitch
Drill Ø
M3
0.5
2.4
M8
1.25
6.6
M4
0.7
3.2
M10
1.5
8.4
M5
0.8
4.1
M12
1.75
10.1
M6
1.0
4.9
